Ultra violet light source



June 2,1942 G. sPER-rl ULTRA VIOLET LIGHT SOURCE Filed Aug. 3, 1940INVENTOK GEORGE SPE-Rn. @llaa v ATTORNEYS.

Patented June 2, 1942 ULTRA VIOLET LIGHT soUncE George Sperti,Covington, Ky., assigner to Science Laboratories, Inc., Norwood, Ohio, acorporation of Ohio Application August 3, 1940, Serial No. 350,425

9 Claims.

Figure 1 is a longitudinal sectional view of the' light source showingthe assembly of parts exelusive of the base.

Fig. 2 is an end elevational view of one of the electrode structures.

Fig. 3 is a sectional view of the electrode structure taken along thelines 3 3 of Fig. 2.

Fig. 4 is av Wiring or .circuit diagram illustrative oi the operation ofthe light source.

The light sources to which my invention is particularly addressed arelight sources combining an arc discharge in an ionizable atmosphere,preferably though not necessarily containing mercury, with means forgiving radiation in the visible spectrum. Lamps of this type though theyhave utility for periodic therapy, activation or sterilizationtreatments are nevertheless of high value for use as or in connectionwith sources of visual light; and the envelope may be so chosen inconnection with the intensity of the ultra violet radi-ation produced bythe light sources as to eliminate not only the irritant effect of theshorter ultra violet Wave lengths but also any tendency to harm theunshielded eye. Consequently the light sourceslare of utility forcontinuous use in school rooms and the like and further as set forth inmy copending application entitled Sources of visual and ultra. violetradiation, Serial No. 350,424, filed August 3, 1940, are useful forcolor work and the like. f

Referring to the drawing, I have indicated at I an envelopepervioustoultra violet radiation but preferably having a filtering effect thereon.The envelope may be of quartz or any of the glasses pervious to ultra,violet light, such for example as Corex. `The envelope is provided witha press 2 through which pass and into which are fused the power leads Iand 5. 'I'he press has a scalable tube 6* as a part of it, through whichtube the atmosphere and degree of evacuation of the envelope arecontrolled in the manufacture of the light source.

- The power lead 5 within the envelope bears an electrode assemblyindicated generally in Fig. 1 at E. An insulative tube 6 which may be ofordinary glass or of the same material as the envelope is fused to thepress so as to be rigid therewith and carries internally the lead I. Thetube 0 extends nearly to the opposite end of the envelope and at thatend the lead 4 or a member fused to it bears the second electrodeassembly E which is indirectly supported thereby. The filament F whichwill be described more in detail hereinafter passes between theelectrode structures and is attached to the respective power leads. Thelila-ment throughout its length at suitable intervals is supported byengagement means 9 having an attachment I0 to the tube 6. My lightsource may be made more resistant to shocks by supporting the outer endof tube B. I have shown this accomplished by a Wire member l, which maybe bent in a serpentine fashion to give it greater resiliency, and theend of which may engage the envelope as at 8.

The atmosphere in the envelope will be of suitable composition andpressure to start an arc discharge and the envelope will also containpreferably a small quantity of mercury adapted to be vaporlzed duringthe operation of the light source. In order to make the device selfstarting I provide in connection with each electrode structure a meanswhich, when heated bythe illament, is adapted to give off ions and toionize the adjacent gas.

Moreover since I do not desire to have the arc continuously operativebetween portions of the filament I provide separate arc electrodes.These I conveniently make in the form of an open coil of conductive wireII as most clearly shown in Figs. 2 and 3. The coil has fused to it atone side a bar I2 to tie the convolutions together and to support thecoil, and this bar in turn is fused to the power lead 5. It will beunderstood that the electrode structure at each end of the light sourcemay be the same, and has been so shown. However, for sources designed tooperate only on direct current, I may employ one electrode of the formshown and described herein, and a second electrode not requiringionizing means. The said second electrode may thus be a suitably shapedpiece of any refractory metal.

Within the hollow of the coil II I provide a longitudinallyperforatedlnsulative block I3; and the lament F is threaded in and out of theperforations in the block so that the activation of the filament willheat the block. The block bears a cylindrical metallic sheath I4 4coatedas at I5 with a refractory `oxide or other suitable substance adapted togive oi! electrons when heated. The assembly of the block, sheath, andcoating lies inside the coil il and may be tacked to it by fusion toprevent displacement.

The filament F is a heavy lament, and as indicated, it connects the twopower leads so as to close the circuit between them. The light sourcewill have a suitable base (not shown) which is conveniently of thescrew-base type but may also be of the bayonet type, if desired. It isin either event a two-contact base; and the lamp in its operationrequires no external starting means but only an impedance for balancingthe arc. The impedance may be a choke, a transformer, a resistance, or alight source capable of delivery light in the visual spectrum.

When power is applied to the device the iilament F, completing thecircuit between the power leads is made to glow. 'I'he portions of thefilament passing through the insulative blocks I3 heat these blocks andcause the emissive coating on their sheaths to ionize the adjacentatmosphere within the envelope. The open-work character of the electrodestructures I i facilitates this ionization. When the ionization adjacentthe electrode structures has progressed far enough, an arc begins toform between the electrode structures il and adjacent portions of thefilament F, which, by reason of the resistance of the filament, are atpotentials differing from the potentials of the electrode structures.The initial arc or arcs thus formed, however, rapidly travel along theiilament until they meet, and until the main arc discharge occursdirectly between the electrode structures Il. The construction of mylight source is such that as soon as the main arc is formed the filamentno longer acts as an electrode and is therefore protected from the arc.

My light scurce is fully self starting and self re-starting. It can bemade in convenient sizes and with normal screw bases. Where desired, thebalancing impedance may be enclosed within the base so that no externalimpedance is required.

Modiileations may be made in my invention wtihout departing from thespirit of it.

Having described an exemplary embodiment of my invention I have in theappended claims `set forth the invention which I believe is inherent inmy disclosure.

I claim:

1. In a light source, an envelope, a press at one part of said envelope,a pair of leads passing through said press, one of said leadsterminating adjacent said press within said envelope, a nonconductivetubular support sealed to said press, the other of said power leadspassing. both through said press and through said tubular support to apoint remote from said press, each of said power leads bearing electrodestructures, resilient means on said power lead at the free end of saidtubular support, said resilient means engaging said envelope, and afilament connected between said power leads.

2. In a light source, an envelope, a press at one part of said envelope,a pair oi' leads passing through said press. one of said leadsterminating adjacent said press within said envelope, a nonconductivetubular support rigidly fastened to said press, the other of said powerleads passing both through said press and through said tubular supportto a point remote from said press, each of said power leads bearingelectrode structures, resilient means on said power lead at the free endof said tubular support, said resilient means engaging said envelope,said resilient means comprising a metal member reversely bent to provideincreased resilience, and having a free end engaging said envelope, anda filament connected between said power leads.

3. In a light source, an envelope, a press at one part of said envelope,a pair of leads passing through said press, one of said leadsterminating adjacent said press within said envelope, a nonconductivetubular support fastened to said press the other of said power leadspassing both through said press and through said tubular support to apoint remote from said press, each of said power leads bearing electrodestructures, and a lament within said envelope external to said support,attached to said power leads and substantially paralleling said tubularsupport.

4. In a light source, an envelope, a press at one part of said envelope,a pair of leads passing through said press, one of said leadsterminating adjacent said press within said envelope, a nonconductivetubular support fastened to said press, the other of said power leadspassing both through said press and through said tubular support to apoint remote from said press each bf said power leads bearing electrodestructures, a filament within said envelope attached to said power leadsand substantially paralleling said tubular support, and supporting meansfor said lament comprising means engaging said filament and attached tosaid tubular support.

5. In a light source, an envelope, a press at one part of said envelope,a pair of leads passing through said press, one of said leads ter-`minating adjacent said press within said envelope, a non-conductivetubular support fastened to said press, the other of said power leadspassing both through said press and through said tubular support to apoint remote from said press, each of said power leads bearing electrodestructures, and a filament within said envelope attached to said powerleads and substantially paralleling said tubular support, at least oneof said electrodes comprising a hollow gridlike member, a sheath withinsaid member and bearing an electron emissive coating, said iilamentpassing within and being supported within said sheath so as to heat saidsheath.

6. In a light source, an elongated envelope, a press adjacent one end ofsaid envelope, a pair of leads passing through said press, one of saidleads terminating adjacent said press within said envelope, anon-conductive tubular support fastened to said press, the other of saidpower leads passing both through said press and through said tubularsupport to a point adjacent the other end of said envelope, each of saidpower leads bearing electrode structures, and a filament within saidenvelope attached to said power leads and substantially paralleling saidtubular support, each of said electrodes comprising a hollow grid-likemember, a sheath within said member and bearing an electron emissivecoating, said lament passing within and being supported within saidsheath so as to heat said sheath, said sheath containing a perforatedinsulative block, said filament passing through the perforations in saidblock.

'1. In a light source, an elongated envelope, a press adjacent one endof said envelope, a pair of leads passing through said press, one ofsaid leads terminating adjacent said press within said envelope, anon-conductive tubular support fastened to said press, the other of saidpower leads passing both through said press and through said tubularsupport to a point adjacent the other end of said, envelope, each ofsaid Apower leads bearing electrode structures, anda sheath, andsupporting means for said lamentl comprising means engaging said lamentand attached to said supporting tube.

8. In a light source, an envelope, a press at one part of said envelope,a pair of leads passing through said press, one of said leadsterminating adjacent said press within said envelope, a non-conductivetubular support fastened to said press, the other of said power leadspassing both through said press and through said tubular support to apoint remote from said press, each of said power leads bearing electrodestructures, and a filament within said envelope attached to'said powerleads and substantially paralleling said tubular support, at least oneof said electrodes comprising a hollow grid-like member, a sheath withinsaid member and bearing an electron emissive coating, said iilamentpassing within and being supported within said sheath so as to heat saidsheath, said sheath vcontaining a perforated insulative block, saidlament passing through the perforations in said block, and supportingmeans for said iliament comprising means engaging said filament andattached to said supporting tube.

9. In a light source of the character described, an envelope, a press atone part of said envelope, a tubular vitreous support fused to saidpress, a pair of power leads passing through said press, one of saidleads terminating adjacent said press and near one end of said envelope,the other of said leads passing through said press and said tubularsupport and terminating at a point remote from said press, means forsupporting the free end of said tubular support with reference to saidenvelope, electrode structures at the ends of each lead, at least one ofsaid electrode structures comprising a grid, means inside said gridcoated with anelectron emissive substance, and a filament substantiallyparalleling said tubular support and having its ends respectivelyattached to said leads, said lament intermediate its length passing intosaid means coated with an electron emissive substance so as to heat saidmeans.

GEORGE SPERTI.

